Hurricane Julio has strengthened into a Category 3 storm as it spins toward Hawaii, with maximum sustained winds of 115 mph.

The National Hurricane Center said Thursday evening it expected little change in the storm through Friday before starting to slowly weaken by Friday night.

Julio is more than 1,000 miles behind Hurricane Iselle, which was set to make landfall on Hawaii's Big Island overnight and then send rain and high winds to the rest of the state Friday.

Iselle is barely holding on to hurricane strength, but its outer edges have been bringing rain and wind to the Big Island. Hundreds of people flowed into emergency shelters, flights have been canceled and some communities have lost power.